Iolite Vs. Tanzanite

Iolite is a gemstone composed of magnesium aluminum silicate.^[1] Tanzanite is a popular gemstone and its chemical composition is calcium aluminium silicate.^[2]

Quick Facts on Differences of Iolite and Tanzanite

For a quick recap of the differences iolite and tanzanite:

• For chemical formulas, iolite is Mg2Al4Si5O18 while tanzanite is Ca2Al3(SiO4)3(OH).
• Iolite streaks colorless while tanzanite streaks white.
• While both iolite and tanzanite can be commonly blue, iolite is often colorless and tanzanite is often purple.

Quick Facts on Similarities of Iolite and Tanzanite

The similarities of iolite and tanzanite include:

• Iolite and tanzanite both can be translucent or transparent.
• In terms of crystallography, iolite and tanzanite both are orthorhombic.
• In terms of luster, iolite and tanzanite both are vitreous.
• Iolite's rarity is similar to tanzanite.

Summary of Iolite

Iolite is a mineral that is also known as cordierite. It is a magnesium iron aluminum cyclosilicate that is found in metamorphic and igneous rocks. Iolite is typically blue to violet in color, but it can also be gray, yellow, green, or brown. It has a vitreous to dull luster and a Mohs hardness of 7 to 7.5.

Summary of Tanzanite

Tanzanite is a blue-violet variety of the mineral zoisite, discovered in the Merelani Hills of Tanzania in 1967. It is a relatively new gemstone, but its unique color and rarity have made it a popular choice in jewelry. Tanzanite is a pleochroic gemstone, meaning it displays different colors when viewed from different angles. It can appear blue, violet, or even a reddish-brown color, depending on the lighting and angle of the viewer.

Table Comparison of Iolite vs Tanzanite